Words to describe attached items

We have an object A that is physically attached to object B. What can we call object A? I would have expected to be able to use "attachee", but this is not in the dictionary, or "attaché", but this seems to only apply to a member of an embassy. What can we call object B? Is there a word for "attached to"?

Solution 1:

The question is Words to describe attached items

The answer to this is an attachment However, I am not sure if this is the word you are looking for.

Accessory or Addition could also be used in this context.

​ Attachment noun (PART) an extra piece of equipment that can be added to a machine: C.E.D